Corpus-NZ/Code-Syntax-Expanded · Datasets at Hugging Face

wrong_code stringlengths 3 123	correct_code stringlengths 3 155	explanation stringclasses 101 values	language stringclasses 26 values
$x = 5; print $x	$x = 5; print $x;	Missing semicolon.	Perl
lambda x: x+1	lambda x: x+1	Correct lambda.	Python
Write-Host 'hello'	Write-Host 'hello'	Correct.	PowerShell
int &ref;	int x; int &ref = x;	Reference must be initialized.	C++
const http = require('http'); http.createServer((req,res) => res.end('info')).listen(58);	const http = require('http'); http.createServer((req,res) => res.end('info')).listen(58);	Correct.	Node.js
if (b = 11) {}	if (b == 11) {}	Use ==.	Dart
if y > 89 puts 'output'	if y > 89 puts 'output' end	Add 'end'.	Ruby
List(44,11,72)	List(44,11,72)	Correct.	Scala
void test(); int main(){{test();}}	void test(); // prototype int main(){{test();}}	Declare before use.	C++
if (foo = 33)	if (foo == 33)	Use ==.	R
{ "name": "value" }	{ "name": "value" }	Correct.	JSON
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(39);	const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(39, () => console.log('listening'));	Add callback.	Node.js
let text = String::from("hello"); let borrow=&text; text.push_str("!");	let mut text = String::from("hello"); let borrow=&text; println!("{{}}", borrow); text.push_str("!");	Cannot mutate while borrowed.	Rust
<input type='text' value='hello'>	<input type='text' value='hello' name='value'>	Add name attribute.	HTML
if (c = 54)	if (c == 54)	Use ==.	Scala
let y = 98;	let y = 98;	Correct.	JavaScript
def process(num): return num + 1	def process(num): return num + 1	Correct.	Python
while val > 51 val -= 1	while val > 51: val -= 1	Colon missing after while.	Python
bar = 23	bar=23	No spaces.	Shell
$x = 5; echo $x	$x = 5; echo $x;	Missing semicolon.	PHP
var a int = 'world'	var a string = 'world'	Type mismatch.	Go
<div><p>info</div></p>	<div><p>info</p></div>	Nest properly.	HTML
echo 'output'	echo 'output';	Add semicolon.	PHP
object Order {{ def main(args: Array[String]) = println("test") }}	object Order {{ def main(args: Array[String]): Unit = println("test") }}	Add return type Unit.	Scala
List<int> list = [1,2,3];	List<int> list = [1,2,3];	Correct.	Dart
Post.save();	Post.save().then(()=>{{}}).catch(err=>{{}});	Handle promise.	Node.js
<person><desc>world</desc><age>54</age></person	<person><desc>world</desc><age>54</age></person>	Add closing >.	XML
print 'hello'	print 'hello';	Add semicolon.	Perl
my @arr = (90,98,57);	my @arr = (90,98,57);	Correct.	Perl
for (int i=0; i<17; i++) {{}}	for (int i=0; i<17; i++) {{}}	Correct.	Java
const int x; x = 5;	const int x = 5;	Const must be initialized.	C++
<person name='result'/>	<person name="result"/>	Double quotes.	XML
<table><tr><td>data<td>hello</tr></table>	<table><tr><td>data</td><td>hello</td></tr></table>	Close td.	HTML
SELECT * FROM users WHRE age=92;	SELECT * FROM users WHERE age=92;	Fix WHERE.	SQL
handle	handle()	Add parentheses.	Kotlin
val temp = 'info'	val temp = "info"	Double quotes.	Kotlin
if [ $val = 24 ]; then	if [ "$val" = 24 ]; then	Quote variable.	Shell
title: world value: hello,	title: world value: hello	Remove comma.	YAML
let index: number \| null = null; index.toFixed(63);	let index: number \| null = null; if(index!==null) index.toFixed(63);	Null check.	TypeScript
UPDATE items SET status='hello' WHERE role=21	UPDATE items SET status='hello' WHERE role=21;	Add semicolon.	SQL
x = output	x = 'output'	Quote strings.	Python
yield a	yield a	Correct yield.	Python
function test(a:string){{return a;}} test(26);	function test(a:string){{return a;}} test('value');	Pass correct type.	TypeScript
ArrayList list = new ArrayList();	ArrayList<String> list = new ArrayList<>();	Use generics.	Java
try {{ throw 'info'; }} catch(e) {{}}	try {{ throw new Error('info'); }} catch(e) {{}}	Throw Error objects.	JavaScript
63bar = 10	bar63 = 10	Variable cannot start with digit.	Python
let a = 98; a += 1;	let mut a = 98; a += 1;	Need mut to modify.	Rust
list: - item1 - item2	list: - item1 - item2	Correct.	YAML
'message' + 47	'message' + 47.to_s	Convert int.	Ruby
echo message hello	echo 'message hello'	Quote to prevent splitting.	Shell
int x; System.out.println(x);	int x = 0; System.out.println(x);	Initialize variable.	Java
if a = 27:	if a == 27:	Use == for comparison.	Python
let y = 'result'	let y = "result"	Double quotes.	Swift
if data = 73 {{}}	if data == 73 {{}}	Use ==.	Swift
println('value')	println("value")	Double quotes.	Scala
p {{ color: green }}	p {{ color: green; }}	Add semicolon.	CSS
class = 'result'	class_name = 'result'	'class' is a keyword.	Python
switch(count){{ case 27: break; }}	switch(count){{ case 27: break; default: break; }}	Add default case.	Java
test	test()	Add parentheses.	Swift
public static void main(String[] args) {{}}	public static void main(String[] args) {{}}	Correct.	Java
name: output age: 78	name: output age: 78	Correct.	YAML
val data: Int = 'test'	val data: String = 'test'	Fix type.	Kotlin
item == '86'	item === 86	Use strict equality.	JavaScript
$x = 5; if ($x -eq 5) { Write-Host 'yes' }	$x = 5; if ($x -eq 5) { Write-Host 'yes' }	Correct.	PowerShell
[29, 40, 29	[29, 40, 29]	Close bracket.	Python
WHERE id = '87'	WHERE id = 87	Don't quote integer.	SQL
function compute() {{ return {{key:'value'}} }}	function compute() {{ return {{key:'value'}}; }}	Return object on same line.	JavaScript
$items[8] = 5;	if (isset($items[8])) $items[8] = 5;	Check existence.	PHP
var x = 17;	var x = 17;	Correct.	Dart
disp('test')	disp('test')	Correct.	MATLAB
int[] list = new int[19]; list[19] = 5;	int[] list = new int[19]; if (19 < list.length) list[19] = 5;	Check bounds.	Java
val foo = 25; foo = 21	var foo = 25; foo = 21	Use var for reassignment.	Scala
SELECT name role FROM items;	SELECT name, role FROM items;	Add comma.	SQL
else print('hello')	else: print('hello')	Colon after else.	Python
x = 5; if x > 3, disp('large'), end	x = 5; if x > 3, disp('large'), end	Correct.	MATLAB
const index;	const index = 47;	Initialize const.	JavaScript
function baz(): void {{ return 77; }}	function baz(): number {{ return 77; }}	Return type mismatch.	TypeScript
<hr></hr>	<hr>	Self-closing.	HTML
list.forEach(function(z) {{ console.log(z); }})	list.forEach((z) => {{ console.log(z); }})	Arrow functions are cleaner.	JavaScript
list[35]	if (list.indices.contains(35)) list[35]	Check index.	Kotlin
const item = 90; item = 60;	let item = 90; item = 60;	Cannot reassign const.	JavaScript
int* obj = nullptr; *obj=5;	int* obj = new int; *obj=5;	Allocate memory.	C++
local foo = 54	local foo = 54	Correct.	Lua
class Item {{ int b; }};	class Item {{ public: int b; }};	Make public.	C++
def bar puts 'test' end	def bar puts 'test' end	Correct.	Ruby
let vec=vec![82,62,36]; let first=&vec[0]; vec.push(96);	let mut vec=vec![82,62,36]; let first=vec[0]; vec.push(96);	Copy instead of reference.	Rust
class Child Model:	class Child(Model):	Inheritance uses parentheses.	Python
fs.readFile('config.json', (err,data) => {{ if(err) throw err; }});	fs.readFile('config.json', (err,data) => {{ if(err) {{ console.error(err); return; }} }});	Better error handling.	Node.js
<root><child>text</child></root>	<root><child>text</child></root>	Correct.	XML
if temp = 37	if temp == 37	Use ==.	MATLAB
let mut index=59; let r1=&mut index; let r2=&mut index;	let mut index=59; {{ let r1=&mut index; }} let r2=&mut index;	Only one mutable borrow.	Rust
String item = 'world';	String item = "world";	Double quotes.	Java
arr(80)	if length(arr) >= 80, arr(80), end	Check length.	MATLAB
print('value')	print('value')	Correct.	R
<a href='https://example.com' target='_blank'>	<a href='https://example.com' target='_blank' rel='noopener'>	Add rel for security.	HTML
type MyType = string \| number; let x: MyType = true;	type MyType = string \| number; let x: MyType = 'hello';	Type not in union.	TypeScript
System.out.println('output')	System.out.println('output');	Add semicolon.	Java
jwt.sign({{id:89}}, 'token');	jwt.sign({{id:89}}, 'token', {{expiresIn:'15m'}});	Add expiration.	Node.js
<ul><li>world<li>test</ul>	<ul><li>world</li><li>test</li></ul>	Close li.	HTML
for i=1,66 do print(i) end	for i=1,66 do print(i) end	Correct.	Lua

$x = 5; print $x

$x = 5; print $x;

Missing semicolon.

Perl

lambda x: x+1

Correct lambda.

Python

Write-Host 'hello'

Correct.

PowerShell

int &ref;

int x; int &ref = x;

Reference must be initialized.

C++

const http = require('http'); http.createServer((req,res) => res.end('info')).listen(58);

Correct.

Node.js

if (b = 11) {}

if (b == 11) {}

Use ==.

Dart

if y > 89 puts 'output'

if y > 89 puts 'output' end

Add 'end'.

Ruby

List(44,11,72)

Correct.

Scala

void test(); int main(){{test();}}

void test(); // prototype int main(){{test();}}

Declare before use.

C++

if (foo = 33)

if (foo == 33)

Use ==.

R

{ "name": "value" }

Correct.

JSON

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(39);

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(39, () => console.log('listening'));

Add callback.

Node.js

let text = String::from("hello"); let borrow=&text; text.push_str("!");

let mut text = String::from("hello"); let borrow=&text; println!("{{}}", borrow); text.push_str("!");

Cannot mutate while borrowed.

Rust

Add name attribute.

HTML

if (c = 54)

if (c == 54)

Use ==.

Scala

let y = 98;

Correct.

JavaScript

def process(num): return num + 1

Correct.

Python

while val > 51 val -= 1

while val > 51: val -= 1

Colon missing after while.

Python

bar = 23

bar=23

No spaces.

Shell

$x = 5; echo $x

$x = 5; echo $x;

Missing semicolon.

PHP

var a int = 'world'

var a string = 'world'

Type mismatch.

Go

Nest properly.

HTML

echo 'output'

echo 'output';

Add semicolon.

PHP

object Order {{ def main(args: Array[String]) = println("test") }}

object Order {{ def main(args: Array[String]): Unit = println("test") }}

Add return type Unit.

Scala

List<int> list = [1,2,3];

Correct.

Dart

Post.save();

Post.save().then(()=>{{}}).catch(err=>{{}});

Handle promise.

Node.js

<person><desc>world</desc><age>54</age></person

<person><desc>world</desc><age>54</age></person>

Add closing >.

XML

print 'hello'

print 'hello';

Add semicolon.

Perl

my @arr = (90,98,57);

Correct.

Perl

for (int i=0; i<17; i++) {{}}

Correct.

Java

const int x; x = 5;

const int x = 5;

Const must be initialized.

C++

Double quotes.

XML

<table><tr><td>data<td>hello</tr></table>

<table><tr><td>data</td><td>hello</td></tr></table>

Close td.

HTML

SELECT * FROM users WHRE age=92;

SELECT * FROM users WHERE age=92;

Fix WHERE.

SQL

handle

handle()

Add parentheses.

Kotlin

val temp = 'info'

val temp = "info"

Double quotes.

Kotlin

if [ $val = 24 ]; then

if [ "$val" = 24 ]; then

Quote variable.

Shell

title: world value: hello,

title: world value: hello

Remove comma.

YAML

let index: number | null = null; index.toFixed(63);

let index: number | null = null; if(index!==null) index.toFixed(63);

Null check.

TypeScript

UPDATE items SET status='hello' WHERE role=21

UPDATE items SET status='hello' WHERE role=21;

Add semicolon.

SQL

x = output

x = 'output'

Quote strings.

Python

yield a

Correct yield.

Python

function test(a:string){{return a;}} test(26);

function test(a:string){{return a;}} test('value');

Pass correct type.

TypeScript

ArrayList list = new ArrayList();

ArrayList<String> list = new ArrayList<>();

Use generics.

Java

try {{ throw 'info'; }} catch(e) {{}}

try {{ throw new Error('info'); }} catch(e) {{}}

Throw Error objects.

JavaScript

63bar = 10

bar63 = 10

Variable cannot start with digit.

Python

let a = 98; a += 1;

let mut a = 98; a += 1;

Need mut to modify.

Rust

list: - item1 - item2

Correct.

YAML

'message' + 47

'message' + 47.to_s

Convert int.

Ruby

echo message hello

echo 'message hello'

Quote to prevent splitting.

Shell

int x; System.out.println(x);

int x = 0; System.out.println(x);

Initialize variable.

Java

if a = 27:

if a == 27:

Use == for comparison.

Python

let y = 'result'

let y = "result"

Double quotes.

Swift

if data = 73 {{}}

if data == 73 {{}}

Use ==.

Swift

println('value')

println("value")

Double quotes.

Scala

p {{ color: green }}

p {{ color: green; }}

Add semicolon.

CSS

class = 'result'

class_name = 'result'

'class' is a keyword.

Python

switch(count){{ case 27: break; }}

switch(count){{ case 27: break; default: break; }}

Add default case.

Java

test

test()

Add parentheses.

Swift

public static void main(String[] args) {{}}

Correct.

Java

name: output age: 78

Correct.

YAML

val data: Int = 'test'

val data: String = 'test'

Fix type.

Kotlin

item == '86'

item === 86

Use strict equality.

JavaScript

$x = 5; if ($x -eq 5) { Write-Host 'yes' }

Correct.

PowerShell

[29, 40, 29

[29, 40, 29]

Close bracket.

Python

WHERE id = '87'

WHERE id = 87

Don't quote integer.

SQL

function compute() {{ return {{key:'value'}} }}

function compute() {{ return {{key:'value'}}; }}

Return object on same line.

JavaScript

$items[8] = 5;

if (isset($items[8])) $items[8] = 5;

Check existence.

PHP

var x = 17;

Correct.

Dart

disp('test')

Correct.

MATLAB

int[] list = new int[19]; list[19] = 5;

int[] list = new int[19]; if (19 < list.length) list[19] = 5;

Check bounds.

Java

val foo = 25; foo = 21

var foo = 25; foo = 21

Use var for reassignment.

Scala

SELECT name role FROM items;

SELECT name, role FROM items;

Add comma.

SQL

else print('hello')

else: print('hello')

Colon after else.

Python

x = 5; if x > 3, disp('large'), end

Correct.

MATLAB

const index;

const index = 47;

Initialize const.

JavaScript

function baz(): void {{ return 77; }}

function baz(): number {{ return 77; }}

Return type mismatch.

TypeScript

<hr>

Self-closing.

HTML

list.forEach(function(z) {{ console.log(z); }})

list.forEach((z) => {{ console.log(z); }})

Arrow functions are cleaner.

JavaScript

list[35]

if (list.indices.contains(35)) list[35]

Check index.

Kotlin

const item = 90; item = 60;

let item = 90; item = 60;

Cannot reassign const.

JavaScript

int* obj = nullptr; *obj=5;

int* obj = new int; *obj=5;

Allocate memory.

C++

local foo = 54

Correct.

Lua

class Item {{ int b; }};

class Item {{ public: int b; }};

Make public.

C++

def bar puts 'test' end

Correct.

Ruby

let vec=vec![82,62,36]; let first=&vec[0]; vec.push(96);

let mut vec=vec![82,62,36]; let first=vec[0]; vec.push(96);

Copy instead of reference.

Rust

class Child Model:

class Child(Model):

Inheritance uses parentheses.

Python

fs.readFile('config.json', (err,data) => {{ if(err) throw err; }});

fs.readFile('config.json', (err,data) => {{ if(err) {{ console.error(err); return; }} }});

Better error handling.

Node.js

Correct.

XML

if temp = 37

if temp == 37

Use ==.

MATLAB

let mut index=59; let r1=&mut index; let r2=&mut index;

let mut index=59; {{ let r1=&mut index; }} let r2=&mut index;

Only one mutable borrow.

Rust

String item = 'world';

String item = "world";

Double quotes.

Java

arr(80)

if length(arr) >= 80, arr(80), end

Check length.

MATLAB

print('value')

Correct.

R

Add rel for security.

HTML

type MyType = string | number; let x: MyType = true;

type MyType = string | number; let x: MyType = 'hello';

Type not in union.

TypeScript

System.out.println('output')

System.out.println('output');

Add semicolon.

Java

jwt.sign({{id:89}}, 'token');

jwt.sign({{id:89}}, 'token', {{expiresIn:'15m'}});

Add expiration.

Node.js

<ul><li>world<li>test</ul>

<ul><li>world</li><li>test</li></ul>

Close li.

HTML

for i=1,66 do print(i) end

Correct.

Lua